After leak checks of the Delta II first stage, engineers decided to remove and replace the liquid oxygen fill and drain valve at Launch Complex 17. That work is being completed today without impact to the launch date. Also, preparations are under way at the pad for the arrival of the STEREO payload.

In the Astrotech Hazardous Processing Facility clean room, the STEREO spacecraft was mated to the upper stage booster on Wednesday. Today the integrated payload is being installed into its transportation canister. On Saturday morning, STEREO will be moved to the launch pad for hoisting atop the Delta II.